Welding systems reside at the core of the modern industrial age. From massive automobile assembly operations to automated manufacturing environments, these systems facilitate joining in ever more complicated manufacturing operations. Hot wire welding processes a wire or electrode being heated (e.g., via current) and received by a puddle created by a main heat source (e.g., plasma arc, tungsten inert gas (TIG) welding, metal inert gas (MIG) welding, flux core, among others). The hot wire welding process includes the resistance heating of the up to or near a melting point of such wire. In hot wire welding processes, the formation of an arc is avoided since an arc condition disrupts or overheats the puddle. A wire heated near or close to the melting point of the wire without arcing events is received by the puddle with little or no disruption. In order to prevent a formation of an arc, a welding parameter related to the workpiece can be detected. The welding parameter can indicate an arc condition in which the hot wire welding process can be adjusted.
Additionally, welding may involve, raising, cladding, building up, filling, hard facing, overlaying, joining, and other welding applications. When confronted with a workpiece having a curved surface, an orbital welding processes may be used to rotate the welding head to apply a weld to the curved surface. The most common examples, where orbital welding is used, is the welding of pipe. Pipe welding may include thin wall application where the welding head is rotated about the other surface two piece ends being joined together, alternatively, pipe welding may include deep groove geometries where the welding electrode extends into a grove formed between the two pipes being joined to lay down successive beads of weld material to fill the grove the join the thick walled pipes. Orbital welding systems may include a welding head that is mounted on a guide track or a fixture that clamps or is otherwise supported on the workpiece and rotated to supply a weld. With orbital welding often involves limited visibility of a welding zone with lead cameras and/or trailing cameras.
Accordingly, in conventional orbital welding systems or other track-guided welding systems, the quality of a weld can be affected by the manner in which a tractor unit is mounted onto a guide track because the mounting can affect how smoothly the tractor unit will travel along the guide track. For example, an improperly mounted tractor unit on a track ring can flex as it moves around the track ring. The flexing can cause the tungsten electrode of the weld head that is attached to the tractor unit to move, e.g., the tungsten electrode can angle in when the tractor unit is at the “12 o'clock” position and angle out when it is at the “6 o'clock” position. This can occur when the tractor unit is not firmly mounted on the track, causing “crabbing” based on vibration or jerking. Additionally, mounting mechanisms can be fragile and easily damaged, e.g., binding and damage to tractor unit components can occur due to over-tightening.
In addition, improper alignment of the travel drive gear in the tractor unit to the track gear of the guide track can also cause problems with weld quality and delays in the welding process. For example, if the center of gravity of the weld head shifts due to, e.g., debris on the track gear, the gears on the travel drive gear and track gear can jam, especially if the system was not properly aligned. To reduce the problems associated with misalignment of the travel drive gear to the track gear, the travel speed of conventional tractor units may need to be set to slow.
Further, engagement of the travel drive gear in the tractor unit to the track gear of the guide track is often performed with a cam lever or other such quick-release mechanism. Should the cam lever fail or open while the tractor unit is in operation, the tractor unit becomes freely movable on the guide track. The tractor unit can, therefore, rapidly move to a position of minimum gravitational potential resulting in poor weld quality and possibly injury. For instance, the guide track can vertically oriented such that the tractor unit drives upward. The tractor unit would freely slide down the guide track in the event of accidental disengagement of the travel drive gear.